The present invention relates to a rail engagement apparatus having powered rail engagement wheels for a road vehicle. Further, this invention relates to a vehicle having such an apparatus mounted to it.
As used herein, a road vehicle is a vehicle having wheels which contact a highway or other road, as opposed to only having wheels which roll on rails on a railroad track.
Railroad service crews often have to go to various places along a railroad track in order to make repairs and inspections. Depending upon the type of service which is performed and other factors, the service crew may ride to the work site using a rail vehicle or using a road vehicle, such as a truck or car. Since the best way to a work site may include travel along a road and travel along a railway, service crews and other rail workers often have used road vehicle having a rail engagement or guide wheel apparatus mounted on them. Such cars or trucks may travel along a highway or other road with road wheels engaging the road. Upon getting to an appropriate place along the railway, the rail engagement apparatus is operated such that railway wheels are lowered from the vehicle until the vehicle is bound to the railway. Usually such vehicles include an apparatus at the front of the vehicle which lifts the front road wheels off the ground when two front railway wheels engage rails and an apparatus at the back of the vehicle, which apparatus secures the back of the vehicle to the rails by two back railway wheels. The two back railway wheels allow the regular road wheels to contact the rails or other surface such that the road wheels may provide traction to move the vehicle even when the two front railway wheels and two back railway wheels have secured the vehicle to the rail. When the vehicle wishes to leave the railway, the two front railway wheels and the two rear railway wheels are retracted or lifted up such that the vehicle may again run along the road.
Various structures have been used to allow railway wheels to be attached to road vehicles. Although such structures have been generally useful at moving the railway wheels between an upper position in which the vehicle may travel along a highway or other road and a lower position in which the vehicle travels along a railway, such structures have often been subject to one or more of several disadvantages.
It has been desirable to have a road vehicle which can also move loads along a railroad track. Various vehicles having rubber tires for highways and rail guide wheels for rails have been used to move railway freight cars with varying degrees of success. Such road/rail vehicles may advantageously move along highways until they reach a railroad track where they can lower their rail engagement wheels and travel along the railroad track. They may then move loads such as rail bound vehicles secured to a rail/highway vehicle. Such rail/highway vehicles may work satisfactorily for some purposes, but the rubber road tires wear out and rapidly fail at higher loads. That is, such rail/highway vehicles are powered by the rubber road tires even though they are bound to the rails when their rail engagement wheels are down. When the loads on the rubber road tires are too high, the tires simply wear out rapidly.
Special vehicles for moving freight cars have been developed, but they are limited to very slow road speeds. These vehicles are basically small locomotives having rail engagement wheels which do not raise and lower. Instead, such small locomotives are modified to have rubber tires which raise and lower such that the vehicle can travel on road surfaces off of rails. However, the special tire mounting and drive arrangements for the rubber tires greatly restrict the road speed of such vehicles. Such vehicles travel on road surfaces by using frictional contact between driven rail engagement wheels and road wheels which have been lowered to a road position. In other words, such special vehicles can travel independent of the rails from one side of a rail yard to another side, but cannot be used on a regular road without going so slowly as to substantially impede the flow of other traffic. More importantly, such vehicles do not use road vehicle frames (meaning frames of cars, trucks, or other street legal vehicles). Instead, they use locomotive or other rail vehicle frames and are accordingly not street legal for normal transit on a highway or other road.
Regular locomotives have often been used for moving freight or other rail cars along light traffic density outlying rail lines. For example, if a given manufacturer is sending two freight cars a day to a rail yard on further travel, a locomotive could be used to move the two freight cars. (Alternately, the locomotive would pick up freight cars at the manufacturer only after a larger number of freight cars are ready, but this may slow the manufacturer's ability to ship in timely fashion.) If the locomotive is tied up moving a small number of freight cars, it cannot be used at other locations where its great power is needed. Further, moving the locomotive by rail to the rail line adjacent the manufacturer's plant requires that track occupancy and rail signaling be handled properly so that the locomotive is switched to the right path and does not collide with (or cause significant delays for) other trains using some of the same tracks.
The present inventor's prior U.S. Pat. Nos. 5,154,124, issued Oct. 13, 1992, and 5,186,109, issued Feb. 16, 1993, both assigned to the assignee of the present application, relate to different apparatus for moving a highway vehicle along a railroad track. Both of those patents are hereby incorporated by reference.